Abstract: A method is disclosed for communication between a plurality of stations. The method includes selecting a master station, which becomes responsible for building and broadcasting at least one service information table (such as the tables defined in MPEG or DVB), and communicates with the (N−1) to the other stations, known as slave stations, in a limited number of situations corresponding to modifications of the content of the tables and according to a specific table management, where the master station is always in one of three states that are either a waiting state, or a building state, or a transferring state, and specific communication rules for the slave stations and the master station.

Abstract: Arrangement for variable-length encoding of digital signals, divided into N parallel paths, comprising a routing circuit which, after classification of the encoded signals in accordance with their lengths and classification of the buffer memories in accordance with their filling states, apply those signals to the buffer memories which are less filled as said signals are longer, said routing circuit being arranged between a variable-length encoding circuit and rate control circuit. The corresponding decoding arrangement, which receives said encoded signals in regrouped data blocks accompanied by a respective path indicator for said blocks, comprises, at the output of an inverse quantization circuit, a circuit for routing said blocks as a function of the associated path indicator.

Abstract: A high definition image transmission system comprising a stage for the transmission of encoded data representative of images and, after transmission of these data at a specific field frequency and by a first channel having a limited passband, a stage for receiving the transmitted data. The transmission stage comprises an image encoding device having three processing channels in parallel for the purpose of transmission, at three separate transmission rates, of one or another of these three channels depending on the output signal of a decision circuit. It further comprises a device for decoding the encoded data, comprising three processing branches located in parallel and each receiving the sequence of the encoded data and a circuit for routing the outputs of the said branches according to the output signal of the decision circuit transmitted to the decoding device by a second channel called the digital assistance channel.

Abstract: In a device for spatio-temporal sub-sampling of digital video signals representing a succession of interlaced or sequential images divided into blocks of m.times.n points (m and n being positive integers), the device comprising, in series, a circuit for the spatial prefiltering of the said sequence of fields, which circuit is intended to deliver a succession of sequential images which are limited with respect to the bandwidth, a spatial sub-sampling circuit, and a temporal sub-sampling circuit: a motion estimator which on the basis of, on the one hand, signals corresponding to the even fields and on the other hand, signals corresponding to the odd fields, delivers one or more information items on the motion in an odd field with respect to the which surround it.

Abstract: In this system a transmission of certain high definition picture elements is provided such that at the receiving side it is possible to recover a picture of the normal definition without it being necessary to use additional circuits.

Abstract: A frequency-modulated digital signal demodulator includes a digital quadrature filter having n elements arranged in cascade, each delaying the input signal by a value T.sub.E =1/F.sub.E, where F.sub.E is the sampling frequency, a number of channels arranged in parallel with the cascade arrangement of delay elements, each channel having a multiplier for multiplying by a given coefficient, a first and a second summing circuit for summing the respective output signals of said multipliers, the output signals of the two summing circuits constituting the quadrature output signals of the filter and being referred to as reference and phase-shifted signals. At the output of the filter a circuit for calculating the instantaneous phase .phi..sub.n of successive signal samples is provided.

Abstract: A system for the transmission of high-definition television pictures in narrow-band channels, and a transmitter and a receiver appropriate to the system. The system includes a transmitting section (10) and a receiving section (20). To transmit the picture via a narrow-band channel (30), the picture produced by a camera (35) is subsampled by a circuit (40). One filter out of a plurality of anti-aliasing filters (F1, F2, . . . , Fn) is selected by means of a movement detector (48); the information of this detector is also transmitted to the receiving section (20) to select, in agreement therewith, one filter output of a plurality of filters (I1, I2, . . . , In) to be used for the oversampling operation.